into selected EOMs. Injections into the EOMs are performed with the use of a portable electromyographic device, although experienced practitioners often dispense with electromyography. In adults, injections are performed with topical anesthetic; in children, general anesthesia is usually necessary.

Clinical trials using botulinum for the treatment of strabismus have shown this agent to be most effective in the following conditions:

small-to moderate-angle esotropia and exotropia (<40Δ)

postoperative residual strabismus (2–8 weeks following surgery or later)

acute paralytic strabismus (especially sixth nerve palsy; sometimes fourth nerve palsy), to eliminate diplopia while the palsy resolves

cyclic esotropia

active thyroid eye disease (Graves disease) or inflamed or pre-phthisical eyes, when surgery is inappropriate

as a supplement to medial rectus muscle recessions for large-angle infantile esotropia or lateral rectus muscle recessions for large-angle exotropia

Multiple injections may be required, particularly in adults. As with surgical treatment, results are best when there is fusion to stabilize the alignment. Botulinum injection is usually not effective in patients with large deviations, restrictive or mechanical strabismus (trauma, chronic thyroid eye disease), or secondary strabismus wherein a muscle has been overly recessed. Injection is ineffective in A and V patterns, dissociated vertical deviations, and chronic paralytic strabismus. The long-term recovery rate for patients with acute sixth nerve palsy treated with observation alone is similar to that of patients who receive botulinum.

Complications

The most common adverse effects of ocular botulinum treatment are ptosis, incomplete eyelid closure, dry eye, and induced vertical strabismus after horizontal muscle injection. These complications are usually temporary, resolving after several weeks. Rare complications include scleral perforation, retrobulbar hemorrhage, pupillary dilation, and permanent diplopia. Systemic botulism has been reported in animals and humans following massive injections of large muscle groups, but this has not been encountered in ophthalmologic use of botulinum toxin.

Gardner R, Dawson EL, Adams GG, Lee JP. Long-term management of strabismus with multiple repeated injections of botulinum toxin. J AAPOS. 2008;12(6):569–575.

Related Videos

The following videos contain additional information on topics covered in this chapter and are available at https://aao-resources-enformehosting.s3.amazonaws.com/resources/AAO.LMS/BCSC151 6/section6.html.

Limbal Incision (1 min, 13 sec)

Fornix Incision (1 min, 43 sec)

Recession of Medial Rectus Muscle (1 min, 13 sec; 2 min, 8 sec)

Resection of Lateral Rectus Muscle (3 min, 2 sec)